This invention relates to an electronic control device for automatically increasing an idle RPM level of an engine of a motor vehicle above a normal idle RPM to a higher preselected maximum idle RPM level to increase output voltage of an engine driven alternator to prevent or at least limit the rate of discharge of a storage battery of the vehicle. So long as the device is activated, the maximum RPM level is maintained regardless of variations in loading on the engine.
Broadly speaking, the idle RPM or idle speed of an internal combustion engine of a motor vehicle has long been controlled by electronic devices of the prior art. For example, modern automobile engines use a conventional electronic control module or ECM to control the normal idle speed of a vehicle engine, the normal idle speed usually being about 800 RPM in a standard internal combustion engine when running in a normal operating temperature range. Upon start-up of the engine, when cold, as when the vehicle has been inoperative for a long period of time in a wintry low temperature environment, the ECM will operate on start-up to increase the idle RPM to about 1000-1100 RPM, to aid in warming up the cold engine and to increase the operating temperature of various temperature sensitive components such as a catalytic converter and an oxygen sensor in the engine exhaust system. Once the engine has warmed up to a temperature at or near its normal operating temperature range, the ECM will operate to reduce the idle RPM back to the normal 800 RPM level and, thereafter, maintain that level subject to reductions that may occur due to variations in the loading on the engine.
In U.S. Pat. No. 5,998,881, granted to R. C. Wind et al. on Dec. 7, 1999, an apparatus and method is disclosed for reducing the idle speed of a vehicle engine from the normal 800 RPM idle level to a low level of about 500 RPM to improve vehicle fuel economy and reduce vehicle emissions. None of the aforementioned devices or methods of the prior art use an electronic device to increase engine idle RPM above normal idle RPM and maintain such an increased idle RPM at a preselected level regardless of engine load variations in response to a low vehicle electrical system output voltage in order to increase the output voltage so as to prevent a disruptive vehicle battery discharge and damage to an alternator of the electrical system. It would be advantageous to provide such a device for use in a motor vehicle, particularly a vehicle which is sometimes parked with the engine running at idle speed for long periods of time, during which periods there is a moderate to heavy demand for electrical energy being placed on an alternator of the vehicle by various electrical components and sub-systems used by the engine and vehicle. A police cruiser is an example of a vehicle which has numerous specialized electrical and electronic systems which can place a heavy energy demand upon the vehicle alternator while the vehicle is parked, as at an accident scene, running at idle speed for a long period of time. Because of such routine operating conditions, the storage batteries and alternators in police vehicles often require relatively frequent replacement, all at substantial cost. In addition, the inconvenience and danger that can also result in leaving a police officer stranded with an inoperative vehicle and dead battery as, for example, at a rural accident site or emergency scene (out of range of a hand held transceiver to the nearest police radio repeater), in the dark of night in severe winter weather with no high powered mobile radio communications link to his or her dispatcher and with no use of other electrical and electronic systems ordinarily available in an operative police vehicle, can be a serious problem.
Because the battery in a police cruiser is frequently discharged in the normal course of cruiser operation, the battery usually must be replaced frequently. Moreover, because the alternator of the cruiser is frequently required to deliver heavy current to such a severely discharged battery at or above its total rated maximum output, the alternator, likewise, must frequently be replaced.
Another prior art engine idle control apparatus is manufactured and sold in this country by Response Technologies, Inc. of Flanders, N.J. This apparatus, sold as a TCS-100 automatic engine idler, increases the idle speed of a motor vehicle engine from a normal idle RPM level to a higher RPM level in response to a low output voltage of the vehicle electrical power generating system, but does so by activating a vacuum servomechanism to open a fuel throttle of the engine by a calibrated or measured amount. Then, when the output voltage of the system increases to a preselected maximum value, the apparatus operates to, in turn, cause the servomechanism to close the throttle by the same calibrated or measured amount.
A difficulty encountered with this type of apparatus is that the higher RPM level is dependent upon loading and load variations on the engine. In other words, heavy loading or load variations on the engine will cause the higher RPM level to be reduced or subject to variations. Also, the chain or cable running from the servomechanism to the engine throttle will be subject to small length changes with age and variations in ambient temperature which can effect the amount of opening of the throttle and, thus, effect the higher RPM level sought to be obtained. Further, if the chain or cable were to fail, as for example, by reason of aging, rust or the like, the apparatus would be rendered inoperative. Finally, the subject apparatus does not control idle RPM level in the same manner as does an ECM of the vehicle.
By means of my invention, these and other shortcomings of the prior art are substantially eliminated.
It is an object of my invention to provide a device for controlling the idle speed of an engine of a motor vehicle to maintain a high output voltage level of an engine driven alternator of an electrical power generating system of the vehicle to prevent a disruptive discharge of a storage battery of the system.
It is a further object of my invention to provide an electronic device for increasing the idle speed of an engine of a motor vehicle to increase the output voltage of an engine driven alternator of an electrical power generating system of the vehicle to supply electrical load requirements of electrical components of the engine and vehicle without severely discharging a storage battery of the system.
It is also an object of my invention to provide a process or method for closely controlling an idle RPM of an engine of a motor vehicle, independent of engine loading, for preventing or at least limiting a disruptive discharge of a storage battery of an electrical power generating system of the vehicle.
It is another object of my invention to provide a device and method for closely controlling idle speed of an engine of a vehicle, regardless of engine loading, in response to low voltage output of an electrical power generating system of the vehicle to minimize vehicle storage battery discharge and damage to a vehicle alternator.
Briefly, in accordance with the objects of my invention, there is provided a device for assuming control of an idle speed control apparatus of an engine of a motor vehicle which is normally controlled by an ECM of the vehicle, the device comprising means for monitoring an output voltage of an electrical power generating system of the engine and vehicle. The device also includes means responsively connected to the monitoring means for generating a first signal indicative that the output voltage is less than a first preselected minimum value. The device further includes means responsively connected to the first signal generating means for generating a second signal which is capable of controlling the idle speed control apparatus of the engine to increase an idle speed of the engine from a normal idle speed level to a higher preselected maximum idle speed level. The device still further includes means responsively connected to the first signal generating means for switching control of the idle speed control apparatus from the ECM to the second signal generating means in response to the first signal.
These and other objects, features and advantages of my invention will become apparent to those skilled in the art from the following detailed description and attached drawings, upon which, by way of example, only the preferred embodiments of my invention is illustrated.